There is known an electrical toothbrush of a type in which teeth are brushed (removal of food residue and plaque) by placing a brush that is vibrating or rotating at high speed on the teeth. Recently, a high value added product having the function of being able to switch the operation mode (number of vibrations, vibration pattern, etc.) of the brush has appeared. In such an electrical toothbrush, an appropriate brush angle (angle formed by brush and tooth axis) and an operation mode are recommended to be selected according to the brushing site. For example, when brushing the periodontal pocket (between tooth and gum), the tip of the hair of the brush easily enters the periodontal pocket if the brush is placed at 45 degrees with respect to the tooth axis and thus is effective in removing the plaque. When brushing the side surface (tooth surface) of the tooth, the brush is to be placed at 90 degrees with respect to the tooth axis, and the operation mode in which the stimulation to the gum is small is desirably selected.
In Patent Document 1, there is proposed a method of determining the position and the movement of the brush using an acceleration sensor, an earth magnetic field sensor, and an angular speed sensor, and evaluating the good and bad of the brushing operation of the user.